The present invention relates to an assembly of units for controlling an electronic apparatus designed to control a robot, such as a manipulation of a spray gun for spraying geometrically undefined workpieces and/or for spraying paint or varnish harmful to man, in suitable working programs.
Such "robots" comprise mechanical, hydraulic, and electronic parts.
The mechanical part carries a painting or varnishing gun, fitted to one end of a succession of arms connected to one another by articulated joints to provide a gun manipulator which possesses mobility of the single arms or parts, relative to one another.
The hydraulic part effects the moving of the arms or elements, by oil hydraulic actuators of known kind, for example, cams, cylinders and hydraulic motors.
The electronic apparatus is provided for cyclically repeating the robot's operations, for example ensuring the carrying out of the painting or varnishing operation as stored in a program storage unit.
The carrying out of the program's operating phases is ensured by transducers which control the exact position of the single arms or other single components of the mechanical part, by electric pulses sent to a central control unit.
The central control unit, if the electric signals generated by the controlling transducers do not agree with electric signals stored in the working storage unit, sends the required electric pulses to a servovalve control of the oil hydraulic actuators until the positional errors of the varnishing guns are fully eliminated. Similar programming is applied to the control of paint or vanish emission by the operating paint gun.
Several technical possibilities, relating to the storage of the varnishing or painting operating phases in the storage unit, are known.
A first possibility consists in developing a program to be stored which renders as close as possible all operating phases of the "robot." A drawback of this possibility is the rather heavy cost of development of such a program, so that such a technique is only justified for costly objects to be painted. Another drawback is due to the fact that the program is possible only for simple geometric-outline objects.
Another possibility is based upon an operating "robot" for transforming the data relating to the spatial and directional position of the spray gun and to the amount of varnish or paint delivered by the same into suitable electric signals to be stored in the working storage unit of the electronic apparatus, by cooperation of a skilled operator with an operating robot manipulator which with a gun, controlled by the operator's hand, varnishes or paints a suitable object as required. This possibility too entails several drawbacks. A first drawback is caused by the considerable friction effects and the inertia in the controlling "robot." Another drawback, consequent to the first one, is caused by the poor controllability of the group "spray gun--robot" entailing an inevitable inaccuracy in the varnishing of an object controlled by the operator, especially when dealing with objects presenting irregular surfaces.